Method of heat treating a Ni-based superalloy article and article made thereby

Abstract

A method of heat treating an Ni-base superalloy article is disclosed. The method includes hot-working an article comprising an NiCrMoNbTi superalloy comprising, in weight percent, at least about 55 Ni to produce a hot-worked microstructure; solution treating the article at a temperature of about 1600° F. to about 1750° F. for about 1 to about 12 hours to form a partially recrystallized warm-worked microstructure; and cooling the article. The method also includes precipitation aging the article at a first precipitation aging temperature of about 1300° F. to about 1400° F. for a first duration of about 4 hours to about 12 hours; cooling the article to a second precipitation aging temperature; precipitation aging the article at a second precipitation aging temperature of about 1150° F. to about 1200° F. for a second duration of about 4 hours to about 12 hours; and cooling the article from the second precipitation aging temperature to an ambient temperature.

1. An NiCrMoNbTi superalloy article having a partially-recrystallized, warm-worked microstructure and comprising, in weight percent, about 55.0-63.0% Ni, about 19.0-22.5% Cr, about 6.5-9.5% Mo, about 2.75-4.5% Nb, about 1.0-2.3% Ti, up to about 0.35% Al, up to about 0.35% Mn, up to about 0.20% Si, up to about 0.010% S, up to about 0.20% C and up to about 0.015% P, with the balance Fe and incidental or trace impurities. 
     
     
       2. The article of  claim 1 , wherein the alloy composition further comprises, in weight percent: up to about 0.05 V, up to about 0.05 Ta, up to about 1.0 Co or up to about 0.02 B, or a combination thereof. 
     
     
       3. The article of  claim 1 , wherein C, Ti and Nb in any combination act as hardening constituents, and wherein, in weight percent, C is about 0.007 to about 0.011, Ti is about 1.33 to about 1.92, Nb is about 3.47 to about 4.07 and the total amount of Ti+Nb is about 4.99 to about 5.40, and the total amount of hardening constituents in atom percent is about 4.39 9 to about 4.97. 
     
     
       4. The article of  claim 1 , wherein the Ni-base superalloy has a 0.2% yield strength of at least about 187 ksi at about room temperature and at least about 165 ksi at about 750° C., an RA of at least about 24% at about room temperature and at least about 31% at about 1150° C. and a hold time crack resistance at 593° C. in air, a stress intensity factor of about 28 ksi-in½ with a load of about 1099 lbs. of at least about 2400 hours. 
     
     
       5. The article of  claim 1 , wherein the alloy composition comprises, by weight: about 59.0-63.0% Ni, about 19.0-22.5% Cr, about6.5-9.5% Mo, about 2.75-4.5% Nb, about 1.0-2.3% Ti, up to about 0.35% Al, up to about 0.20% Mn, up to about 0.20% Si, up to about 0.010% S, up to about 0.20% C and up to about 0.015% P, with the balance Fe and incidental or trace impurities; or about 55.0-59.0% Ni, about 19.0-22.5% Cr, about 6.5-9.5% Mo, about 2.75-4.5% Nb, about 1.0-2.3% Ti, up to about 0.35% Al, up to about 0.35% Mn, up to about 0.20% Si, up to about 0.010% S, up to about 0.03% C and up to about 0.015% P, with the balance Fe and incidental or trace impurities. 
     
     
       6. The article of  claim 1 , wherein the article comprises a turbine component, the turbine component comprising a blade, vane, rotor, stator, spacer, shroud, liner, nozzle, steam valve or combustor.